Set empty collections to nil value

generator/generator_test.go

@@ -57,7 +57,7 @@ func TestGenerator_Generate(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	expect := "h1:fax3XoUdX25uZP33jy/p8dN8fz9KyBkodgokFpmho14="
+	expect := "h1:4zaocS5qbH8uRHYYKVq6ohH4QevkDfTBqm6PhUgTbrI="
 	received, err := dirhash.HashDir(dir, "", dirhash.DefaultHash)
 	if err != nil {
 		t.Fatal(err)
@@ -68,6 +68,54 @@ func TestGenerator_Generate(t *testing.T) {
 	}
 }
 
+func TestGenerator_Generate_FailureCases(t *testing.T) {
+	for _, test := range []struct {
+		name  string
+		dir   string
+		mkdir bool
+	}{
+		{"No permissions to create directory", "/mint-test-run", false},
+		{"Destination exists, but is a file, mkdir false", "testdata/some-file-treated-as-a-directory", false},
+		{"Destination exists, but is a file, mkdir true", "testdata/some-file-treated-as-a-directory", true},
+		{"Destination does not exist", "/tmp/some/destination/directory/that/does/not/exist", false},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			ast, err := parser.ParseDir("testdata/valid-documents")
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			opts := &GeneratorOptions{
+				PackageName:   "mint_testrun",
+				MakeDirectory: test.mkdir,
+				Directory:     test.dir,
+				Clobber:       true,
+			}
+
+			g, _ := New(ast, opts)
+
+			t.Run("generate skeletons on", func(t *testing.T) {
+				g.CustomFunctionSkeletons = true
+
+				err = g.Generate()
+				if err == nil {
+					t.Errorf("expected error, received none")
+				}
+			})
+
+			t.Run("generate skeletons off", func(t *testing.T) {
+				g.CustomFunctionSkeletons = false
+
+				err = g.Generate()
+				if err == nil {
+					t.Errorf("expected error, received none")
+				}
+			})
+
+		})
+	}
+}
+
 func TestGenerator_generateType(t *testing.T) {
 	g := new(Generator)
 

generator/types_test.go

@@ -163,6 +163,10 @@ func (sf *SomeTestType) unmarshallSomeStringSlice(r io.Reader) (err error) {
 	if err != nil {
 		return
 	}
+	if f.Len() == 0 {
+		sf.SomeStringSlice = nil
+		return
+	}
 	f.V = make([]mint.MarshallerUnmarshallerValuer, f.Len())
 	for i := range f.V {
 		f.V[i] = mint.NewStringScalar("")
@@ -198,6 +202,10 @@ func (sf *SomeTestType) unmarshallSomeStringSlice(r io.Reader) (err error) {
 	if err != nil {
 		return
 	}
+	if f.Len() == 0 {
+		sf.SomeStringSlice = nil
+		return
+	}
 	for i := 0; i < f.Len(); i++ {
 		f.V[mint.NewStringScalar("")] = mint.NewInt64Scalar(int64(0))
 	}

generator/unmarshallers.go

@@ -69,7 +69,10 @@ func (g Generator) unmarshallMap(t string, e parser.AnnotatedEntry) jen.Code {
 			jen.If(jen.Id("err").Op("!=").Id("nil")).Block(
 				jen.Return(),
 			),
-
+			jen.If(jen.Id("f").Dot("Len").Call().Op("==").Lit(0)).Block(
+				jen.Id("sf").Dot(e.Name).Op("=").Id("nil"),
+				jen.Return(),
+			),
 			jen.For(jen.Id("i").Op(":=").Lit(0), jen.Id("i").Op("<").Id("f").Dot("Len").Call(), jen.Id("i").Op("++")).Block(
 				jen.Id("f").Dot("V").Index(jen.Add(keyInitialiser).Call(keyNilValue)).Op("=").Add(valueInitialiser).Call(valueNilValue),
 			),
@@ -112,6 +115,10 @@ func unmarshallSlicePreludeGetLen(e parser.AnnotatedEntry) []jen.Code {
 		jen.If(jen.Id("err").Op("!=").Id("nil")).Block(
 			jen.Return(),
 		),
+		jen.If(jen.Id("f").Dot("Len").Call().Op("==").Lit(0)).Block(
+			jen.Id("sf").Dot(e.Name).Op("=").Id("nil"),
+			jen.Return(),
+		),
 		jen.Id("f").Dot("V").Op("=").Id("make").Call(jen.Index().Qual(mintPath, "MarshallerUnmarshallerValuer"), jen.Id("f").Dot("Len").Call()),
 	}
 }

generator/unmarshallers_test.go

@@ -13,6 +13,10 @@ var (
 	if err != nil {
 		return
 	}
+	if f.Len() == 0 {
+		sf.SomeStringSlice = nil
+		return
+	}
 	f.V = make([]mint.MarshallerUnmarshallerValuer, f.Len())
 	for i := range f.V {
 		f.V[i] = mint.NewStringScalar("")
@@ -77,6 +81,10 @@ func TestGenerator_unmarshallMap(t *testing.T) {
 	if err != nil {
 		return
 	}
+	if f.Len() == 0 {
+		sf.SomeStringSlice = nil
+		return
+	}
 	for i := 0; i < f.Len(); i++ {
 		f.V[mint.NewStringScalar("")] = mint.NewInt64Scalar(int64(0))
 	}